The present invention relates to prosthetic heart valves. More particularly, it relates to a device and method for functionally replacing a deficient, previously implanted prosthetic heart valve.
Implantable heart valve prostheses have long been used to replace various diseased or damaged natural aortic valves, mitral valves, pulmonic valves, and tricuspid valves of the heart. The actual shape and configuration of any particular prosthetic heart valve is, of course, dependent upon the valve being replaced. Generally, the known heart valve prostheses are either bioprostheses or mechanical heart valve prostheses.
The bioprostheses or “tissue valves” are generally made of a suitable animal tissue or materials (e.g., harvested porcine valve leaflets, bovine or equine pericardial leaflets, synthetic material leaflets, etc.) that may be mounted onto a stationary metal or plastic frame, referred to as a “stent”. Regardless of whether a stent is provided, bioprosthetic/synthetic heart valves are generally tubular (i.e., when the leaflets are “open”, an internal passage is defined through which fluid (e.g., blood) can flow), and include a sewing or suture ring.
The sewing or suture ring provides a means for fixing the prosthetic heart valve to the patient's native heart valve orifice tissue (e.g., native annulus or valvular rim) associated with the native heart valve being repaired or replaced. In particular, an exacting surgical implantation technique is traditionally employed whereby the heart is stopped (cardiopulmonary bypass) and opened followed by surgical removal of damaged or diseased natural valve structure. Subsequently, the prosthetic heart valve is properly oriented within the native valvular area, with the sewing ring being seated against or at the native annulus or valvular rim. Sutures are then used to affix the sewing ring to the natural tissue.
A successfully implanted prosthetic heart valve will normally function without problem for many years. In certain instances, however, deficiencies may become evident shortly after implant or within a few years (especially in younger patients). Common functional deficiencies relate to calcification of the prosthetic heart valve leaflets, stenosis, and prosthetic heart valve insufficiency.
Under these and other circumstances, the prosthetic heart valve does not function properly, or no longer functions properly, and conventionally is surgically removed and replaced. Removal of a previously implanted prosthetic heart valve entails the same surgical intervention described above, coupled with the need to implant a new prosthetic heart valve. As a point of reference, while well-accepted, the conventional surgical intervention described above is difficult to perform and can result in patient injury or more severe complications. In fact, due to physical weakness, implantation of a prosthetic heart valve via the conventional surgical technique may be considered either too high risk or contra-indicated for certain patients. Further, removal of a previously implanted prosthetic heart valve requires cutting of the sutures that otherwise secure the prosthesis to the native annulus/valvular rim, and re-stitching of a new sewing ring. These activities can further compromise the integrity of the valvular rim and lead to recovery complications, morbidity and mortality.
Percutaneously-delivered prosthetic heart valves have been suggested having a generally similar configuration, such as by Bonhoeffer, P. et al., “Transcatheter Implantation of a Bovine Valve in Pulmonary Position.” Circulation, 2002; 102:813-816 and Cribier, A. et al. “Percutaneous Transcatheter Implantation of an Aortic Valve Prosthesis for Calcific Aortic Stenosis.” Circulation, 2002; 106:3006-3008, the teachings of which are incorporated herein by reference. These techniques appear to rely upon a frictional engagement between the expanded support structure and the native tissue to maintain a position of the delivered prosthesis. That is to say, with the transcatheter technique, conventional sewing of the prosthetic heart valve to the patient's native tissue cannot be performed. Similarly, Bonhoeffer, P. et al., “Percutaneous Insertion of the Pulmonary Valve.” J Am Coll Cardiol, 2002; 39:1664-1669, the teachings of which are incorporated herein by reference, describe percutaneous delivery of a biological valve, sutured to an expandable stent, within a previously implanted valved or non-valved conduit, or a previously implanted valve. Again, it appears that radial expansion of the secondary valve stent is the sole means for placing and maintaining the replacement valve.
Prosthetic heart valves continue to be essential tools in the treatment of patient's suffering from cardiac deficiencies. Further, the investigation into percutaneously-delivered prosthetic heart valves appears promising. Unfortunately, the inability to rigidly affix a percutaneous prosthetic heart valve remains problematic. Therefore, a need exists for a prosthetic heart valve and related method of implant that is conducive to percutaneous delivery for replacing a deficient, previously implanted prosthetic heart valve.